The metabolism of erythrocytes obtained from Duchenne and myotonic dystrophy patients will be investigated in in vitro incubation experiments. The premise underlying these studies is that the metabolism of erythrocytes may reflect the metabolism of skeletal muscle with respect to basic alteration that are present in Duchenne and myotonic dystrophies. The basis for the greater ATP content and lactate production that have been observed in preliminary work will be explored by testing whether a plasma factor may be involved and by conducting a crossover analysis of measured glycolytic intermediates. Pilot investigations with 31P NMR (nuclear magnetic resonance) spectroscopy have shown that the concentration of phosphate compounds in erythrocytes from patients with Duchenne and myotonic dystrophies may differ from the phosphorus profile observed in normal erythrocytes. These studies will be completed and extended. Anion permeability studies with radioactive tracers are also contemplated since changes in the membrane transport of small anions may precede the known increase in movement of larger protein molecules across muscle cell membranes. These studies may provide support for the view that a multisystem membrane defect underlies the development of the muscular dystrophies.